Sound control system



A ril 15, 1952 H. SCHWARTZBERG 2,593,204

SOUND CONTROL SYSTEM Filed Feb. 18, 1946 52 32 UL sou/v0 LEVEL CONTROL 5 50225 *WI I P F J T i 54 LOUD isa 2 MICROPHONE SPL'AKEE VOLT/1575A i V QIRcU/Y o l 3 i l flao/ro/wwv l X l 4 FIG I fififi EEVEES/BLE I Mom 52 3 wvs/v 70/? J 5 L Hen/: Sicfiu/arfzber y ||lfi|||| Patented Apr. 15, 1952 UNITED STATES PATENT OFFICE;

SOUND'GONTROL- SYSTEM Henry Schwartzberg, Brookline, Mass.

AnnlicationFebruary 18, 1946;.SerialNo. 648.390.

(01., 1'l7j-3l1) 2'. Claims.

This; invention, relates to an. improved sound control system for sound pictureapparatus.

In systems of thistype as heretofore, cone stituted, it has been customary for an observer in the auditorium of a sound picture theatre to attempt-to judge aurally the proper intensity of sound level with various sizes of the audience, and'to signal theoperator in the booth to either raise or lower the sound intensity until, in; the opinion ofthe observer; the proper level was reached. The usualsign'al device was a buzzer located in the projectionbooth, and a control pushbutton in the auditorium. One buzz indicated that the sound level was too low; two buzzes indicated that the, sound. level was too high. In such a system the observer often is subjected to aural fatigue, thus rendering him incapable of proper judgment. Also, such obser-vershaveoften beenprone ,to neglect signalling the operator except attooinfrequent intervals. As-aresult, the sound reproduction, in the usual sound theatre has. often been, considerably below. satisfactory standards.

An object, of. this invention. it. to produce a simple inexpensive and reliable system which will relieve the auditorium observer from the necessity for exercising, hisaural jud ment, but Which. will nevertheless provide the projection booth operator with continuous instructions as to how to adjustthe sound projectionapparatus for satisfactory auditorium reproduction.

Another object is tointroducea minimum of change in thenature of thesignal reaching the operator, whereby the presentv system may be substituted for previoussystems with a minimum burdenon the operator.

The foregoing and other objects of this invention will be, best understood from the following description ofv exemplifications thereof,reference being had to the accompanying drawing wherein:

Fig. 1 is. a diagrammatic representation of a system incorporating my invention; and

Fig. 2 is afragmentary diagram of a modification of the system shown in Fig. 1.

In the drawing, l represents a. sound picture theatre auditorium, and 2 is the projection booth in which is located a sound level control apparatus 5|, controlled by an adjusting member 52 and feeding, through a pair of leads 53, a loud speaker 54 located in the auditorium I, whereby the operator may adjust the. level of sound supplied to, the auditorium. At av convenient location in the auditorium, receptive of thesound introduced thereinis located a microphone 3. The output of the microphone is fed to a suitable amplifying circuit, such as a vacuum tube voltmeter circuit device 4, the output of which is a voltage, the magnitude of which constitutes a measure of the sound level at the microphone. From the foregoing it is clear that the microphoneand its, amplifying circuit are responsive to substantially all of, the audible frequencies normally contained in such sound. This output voltage. is. impressed across av potentiometer 5. The potentiometer is provided with a plurality of taps, preferably three in number, indicated in the drawing by the reference numerals 6, l and 8. An adjustable contact arm 9 is adapted to be moved into engagement with anyone of: said taps by. the auditoriumobserver. Tap 6. represents the tap onwhichthe army 9 is set when the auditoriumis one-third, full, tap lis contacted whenthe auditorium is two-thirds full, and tap 8 is contacted when the auditorium is full. Thus as the auditorium audiencev increases, a smaller proportion of the output. voltage from the voltmeter circuitdeviceis, impressed between the arm 9 and a conductor- I0 con.- nectedto-theopposite endof thepotentiometer 5.

The conductor 10 and a conductor ll, connected to the arm 9 feed the selected portion of the voltage from the potentiometer 5- to a volt-,- meter- [2. The voltmeter I2- isprovidedwith an indicating needle l3. which, when it is in. its central position indicates a satisfactory normal sound level. If, however, the voltage supplied to it falls below normal, the needle l3 movesto theleft and indicates thatthesound level'is too low. Likewise, if thevoltage rises above'normal, the needle moves to theright and indicates that the-soundlevel istoohigh. The meter, l2 in,.it:- self provides a constant visualindication to. the operatoras. to the conditions of soundlevelj. in the auditorium as. adjusted to the sizeof. the audience.

Thevoltmeter needle l3v also carries acontact M which engages an arcuate contact,v l5. in the low position of the needle and an arcuate contact, I6 in the, high position of the needle. The meter (2 is preferably damped so, as. to respond. only to relatively slowvariations in voltage, thus avoiding, a response to transient variations in sound not requiring-a resetting of the general'sound level. Suitabledelay. may-also be incorporated in the device 4 for the same purpose. The contact Misconnected by a conductor I! to oneside of a suitable sourceofcurrent such as a battery [8. The other side of the battery is connected to a common connection [9 having, one branch 20 connected-to one terminal of an actuating electromagnet 2|, and having another branch 22 connected to one terminal of another actuating electromagnet 23. The contact; [5' is connectedto the'other terminalof the electromagnet 23, and the contact 18 is connected to the other terminal of the electromagnet 2l. The electromagnets 2| and 23 actuate the armature 24 which, when both electro- 31 stops.

3 magnets are deenergized, is maintained in a central position by a biasing spring 25.

The armature 24 carries a contact arm 26 which is adapted to engage a stationary contact 21 when electromagnet 2I is energized, and a stationary contact 28 when electromagnet 23 is energized. The contact arm 26 is also connected by means of a conductor 29 to one terminal of a suitable source of power, such as a battery 30.

The other side of the battery is connected to one terminal of a signalling device, such as a buzzer 3|. is connected to a conductor 32, one branch of which is connected to a brush 33 and another branch of which is connected to a brush 34. The brush 33 engages the slip ring of a commutator 35 having a rotating contact 36. The brush 34 engages the slip ring of a commutator 3i having two rotating contacts 38 and 39 adjacent each other on said commutator. A stationary brush 4!) is adapted to engage the commutator 35, and a stationary brush 4| is adapted to engage the commutator 3'1. Brush 40 is connected to contact 28, and brush II is connected to contact 21.

The commutators 35 and 31 are driven by a motor drive 42, such as a simple clock motor mechanism, which imparts a relatively slow rotation to the commutators, such as one revolution eachtwo seconds. The motor drive 42 may be energized from a suitable source of alternating current.

When initially installed, the system is so designed and adjusted that, with the auditorium one-third full and with the arm 9 set on the tap :6, a proper level of sound at the microphone 3 will cause the needle I3 to assume its normal or central position. The tap I is so located that, with the arm 9 set on it, the sound level which causes the needle I3 to assume its central position is suificiently higher to be proper for the auditorium two-thirds full. Likewise, the tap 8 is so located that, .with the arm 9 set on it, the sound level which causes the needle I3 to assume its central position is sufficiently higher to be proper for the auditorium filled with an audience. I During operation, the auditorium observer notes whether the auditorium is one-third, twothirds or completely full. He then sets the arm '9 on the corresponding tap on the potentiometer 5. If the sound level is proper, the needle I3 will be in its central position, and no signal will be conveyed to the operator by the buzzer 3|. If, however, the sound level falls too low, the contact I4 will engage the contact I5. This will energize the electromagnet 23, which will cause the contact 26 to engage the contact 28. This will connect the commutator 35 into the circuit of the motor drive 42. The single buzz will inform the operator that the sound level is too low, whereupon he will make the proper adjustments to raise the auditorium sound level until the buzzer If the sound level rises too high, the contact [4 will engage the contact I6 which will energize the electromagnet 21 to cause the contact 26 to engage the contact 21. This will con- The other terminal of the buzzer gized to produce a series of double buzzes. This will inform the operator that the sound level is too high, and he will then lower the sound until the double buzzes cease.

By the above arrangement the objects of this invention are accomplished in asimple yet effective manner. Of course it is to be understood that this invention is not limited to the particular details as described above as many equivalents will suggest themselves to those skilled in the art. For example, other means than a potentiometer may be used to select the various sound levels. Also other degrees of audience size may be selected as those at which the adjustments by the auditorium observer are to be made. The signalling system in the booth could be varied as by utilizing other types of signals, such as visual signals. Likewise, instead of causing the sound level to be adjusted through the medium of an operator in the booth, the signal current from the auditorium station could be utilized to automatically raise or lower the sound level, as shown in Fig. 2. In this embodiment the contacts 21 and 28 control a reversible motor 55 which drives the member 52 and this raises or lowers the sound level dependent on the direction of rotation of the motor 55. Other equivalents .will suggest themselves to those skilled in the art. It is accordingly desired that the appended claims be given a broad interpretation commensurate with the invention within the art.

What isclaimed is:

1. A sound control system comprising a moving picture theatre including an auditorium and a projection booth, a microphone device in said auditorium generating a voltage which is a meas-. ure of the sound level in said auditorium, signal means in said booth, means for supplying said voltage to said signal means, said signal means being responsive to voltage below a predetermined normal value of said voltage to produce a single audible signal and responsive to voltages above said predetermined value to produce two sequential audible signals.

2. A sound control system comprising a moving picture theatre including an auditorium and a projection booth, a microphone device in said auditorium generating a voltage which is a measure of the sound level in said auditorium, signal means in said booth, means for supplying said voltage to said signal means, said signal means being responsive to voltages below a predetermined normal value of said voltage to produce a single audible signal and responsive to voltages above said predetermined value to produce two sequential audible signals, and means for adjusting the ratio of said voltage to the intensity of sound in said auditorium.

HENRY SCHWARTZBERG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,331,236 Schaefer Oct. 5, 1943 2,338,551 Stanko Jan. 4, 1944 2,392,218 Anderson- Jan. 1, 1946 2,395,679 Neuhof Feb. 26, 1946 2,398,046 Schaefer Apr. 9, 1946 

